Cnidaria is a phylum within Kingdom Animalia which consists of hydras, jellies (or jellyfish), sea anemones, and corals. All cnidarians are radially symmetrical, and there are two main radially symmetrical body types.
The stock market crash, on black Tuesday (October 29, 1929) began the Great Depression.
The Great Depression Causes And Effects. The Great Depression represents one of the darkest periods in American economic history. Most people think the Great Depression started in October 1929, with the famous Black Tuesday stock market crash, but economists and historians point to an economic downturn which took hold in early 1929.